Fix bug in persistence test (#1728)

This is a left over of local testing that breaks backward compatibility
of modules that return an invariant handler.

Rolling back the local change

Signed-off-by: Francisco Javier Tirado Sarti <ftirados@ibm.com>

Author: fjtirado

impl/persistence/tests/src/main/java/io/serverlessworkflow/impl/persistence/test/AbstractHandlerPersistenceTest.java

@@ -163,10 +163,6 @@ void testWorkflowInstance() throws InterruptedException {
       assertThat(stream.count()).isEqualTo(1);
     }
     definition.close();
-
-    close();
-    handlers = getPersistenceHandlers();
-
     instance =
         (WorkflowPersistenceInstance)
             handlers.reader().find(definition, workflowInstance.id()).orElseThrow();